The present invention relates to a method of producing ceramic articles with relief decoration.
One of the known techniques for relief or three-dimensional decoration of ceramic articles such as porcelains, earthenware and the like involves applying a planar or two-dimensional transfer decal to a relief image on a ceramic article, and then firing the ceramic article with the transfer decal thereon in a kiln at high temperature such that the decorative ceramic inks of the transfer decal is permanently fused onto the surface of the relief image of the ceramic article. The transfer decal has desired image corresponding to the relief image on the ceramic article and typically comprises a backing paper, a water-soluble film of glue on the backing paper, a decorative ceramic ink layer printed on the glue film, and a cover coat layer on the decorative ceramic ink layer. The transfer decal is soaked in the water to separate the decorative ceramic ink layer covered by the cover coat from the backing paper before application to the ceramic article. The ceramic article with relief image on its surface may be obtained by impressing technique or molding which is of known technique.
While it is easy to obtain a transfer decal having aesthetic, colorful, printed title such as scenery, characters, and people, etc., and a ceramic article with a relief image having raised and recessed portions, it is difficult to have the transfer decal adhered to and completely conformed to the ceramic article without any cavities or blisters between the transfer decal and the raised and recessed surfaces of the relief image of the ceramic article. It is known that such cavities or blisters may cause cleavages or shrinkage in the transfer decal when firing the ceramic article. FIG. 1 shows a ceramic article 10 such as a mug having a relief design 14 covered by a transfer decal 16. It can be seen that some spaces or cavities 18 exist between the transfer decal 16 and raised and recessed sections of the relief design 14 standing out from the curved outer surface 12 of the ceramic article 10. In the prior art, it requires many laborious and costly manual operations to eliminate those spaces or cavities.